This invention relates to display devices of semiconductor structure, and, more particularly, to a display device for displaying photographic information in analogue form.
In constructing a display system for displaying photographic information in the field of view of a camera finder, use has been made of a galvanometer with its pointer being supported very delicately so as to be responsive to minute variation of current flowing through the coil of the galvanometer. This mechanical structure gives rise to a high possibility of occurrence of damage at the supporting of the pointer.
A trend in recently developed cameras is, therefore, to employ an array of light-emitting diodes instead of galvanometer for the display purposes. Unlike the galvanometer, the light emitting diode is characterized by certain features, such as the feature that the display can be read out in a dark environment, since visible light emanates from the energized light-emitting diode and the feature that it is possible for the diode to operate with intermittent energization. In addition thereto, there is no possibility of occurrence of the type of damage which would be otherwise encountered when the galvanometer is used, because of the lack of mechanically movable parts. Thus, the durability is remarkably improved. Furthermore, such LED system occupies less space allowing, in general, far more available space in the camera.
The conventional display system using such light-emitting diodes, though providing for many advantages over the galvanometer as described above, are, however, generally designed to display a value of information not in analogue form but in digital form, thereby giving rise the production of other problems. For example, in the case of the dot type display system, it is required to increase the number of light-emitting diodes necessary when the number of values available for a single information is increased. If an intermediate value between two successive available values is desired to be displayed more accurately, (such as corresponding to two light-emitting diodes positioned adjacent to each other which are rendered effective for display), it is impossible to read out how much and to which of these two values the particular intermediate value approaches. In the alternative, in a digital display system using seven-segment read-out elements of light-emitting diode structure for direct display of numeral characters, there is a disadvantage that it takes a somewhat long time to read out the displayed value.
Accordingly, the present invention has for its general object to provide a novel display device of light-emitting diode structure which overcomes the above-mentioned drawbacks of the conventional display system using the light-emitting diodes as the read-out elements and which can display information not in digital form but in a nearly analogue form.
A first object of the present invention is to obtain a single light-emitting diode structure capable of varying the length of a continuous luminous zone.
A second object of the present invention is to provide for nearly analogue display within the field of view of a camera finder by use of the aforesaid light-emitting diode structure.
These and other objects and features of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings.